A public land mobile network (Public Land Mobile Network, PLMN for short) is a network established and operated by a government or an operator authorized by the government, to provide a land mobile communications service for the public. The PLMN is identified by using a mobile country code (Mobile Country Code, MCC for short) and a mobile network code (Mobile Network Code, MNC for short).
If a mobile terminal needs to acquire network services such as voice, data, and multimedia, the mobile terminal first needs to select a suitable PLMN and search for a cell within the coverage of the PLMN, and after finding an available cell, the mobile terminal camps on the cell and initiates registration. The 3rd Generation Partnership Project (The 3rd Generation Partnership Project, 3GPP for short) TS23.122 Protocol stipulates that during automatic network selection, a mobile terminal selects a suitable PLMN according to the following sequence: a registered public land mobile network (Registered PLMN, RPLMN for short), a home public land mobile network (Home PLMN, HPLMN for short), a user controlled public land mobile network (User Controlled PLMN, UPLMN for short), an operator controlled public land mobile network (Operator Controlled PLMN, OPLMN for short), and other PLMNs (Other PLMNs), to register with the network.
However, in the prior art, when the RPLMN and the HPLMN are unavailable, if an automatic network selection mode is used, the mobile terminal randomly sorts PLMNs having good signal quality, and sorts, according to values of signal strength, PLMNs having poor signal quality. In this case, a case in which a forbidden PLMN (Forbidden PLMN, FPLMN for short) having best signal quality has a highest priority and therefore is selected by the mobile terminal to register with the network may occur, and consequently, the mobile terminal needs to select a PLMN and search for a cell multiple times before succeeding in registration. Therefore, network registration performed by the mobile terminal has a relatively low speed and relatively low efficiency.